C# 具有可变长度结构数组的PInvoke/编组

在过去的几天里，我一直在努力用C#来组织一个结构。希望有更多经验的人能帮上忙（结构定义被缩短了一点，所以没有那么多阅读）

HBAAPI定义

HBA_STATUS HBA_GetFcpTargetMapping(
    HBA_HANDLE      handle,
    HBA_FCPTARGETMAPPING *pmapping
);

typedef struct HBA_FCPTargetMapping {
    HBA_UINT32      NumberOfEntries;
    HBA_FCPSCSIENTRY    entry[1];       /* Variable length array
                                         * containing mappings */
} HBA_FCPTARGETMAPPING, *PHBA_FCPTARGETMAPPING;

typedef struct HBA_FcpScsiEntry {
    HBA_SCSIID      ScsiId;
} HBA_FCPSCSIENTRY, *PHBA_FCPSCSIENTRY;

typedef struct HBA_ScsiId {
    char        OSDeviceName[256];
    HBA_UINT32      ScsiBusNumber;
} HBA_SCSIID, *PHBA_SCSIID;

我在C#中的定义是：

我可以得到第一个SCSIEntry，但不能得到后续的SCSIEntry。我知道该定义是一个可变长度数组，但我不知道如何正确声明它，或将数据封送回托管结构

下面的方法有效，但显然只获得1个SCSIEntry

//Allocate only one, supposed to recall with the appropriate allocated size, using NumberOfEntries
IntPtr buffer = Marshal.AllocHglobal(Marshal.SizeOf(typeof(HBA_FCPTARGETMAPPING)));
Uint32 status = HBA_GetFcpTargetMapping(hbaHandle, buffer);
HBA_FCPTARGETMAPPING fcpTgtMapping = (HBA_FCPTARGETMAPPING)Marshal.PtrtoStructure(buffer, typeof(HBA_FCPTARGETMAPPING));

编辑--这看起来对吗？如何获取SCSIEntry阵列

[StructLayout(LayoutKind.Sequential)]
public struct HBA_FCPTARGETMAPPING
{
    public UInt32 NumberOfEntries;
    public IntPtr SCSIEntry;    /* Variable length array containing mappings*/
}

//Alloc memory for 1 FCPTargetMapping to get the number of entries
int singleBufferSize = Marshal.SizeOf(typeof(HBA_FCPTARGETMAPPING));
IntPtr singleBuffer = Marshal.AllocHGlobal(singleBufferSize);
uint singleResult = HBA_GetFcpTargetMapping(hbaHandle, singleBuffer);
HBA_FCPTARGETMAPPING singleFCPTargetMapping = (HBA_FCPTARGETMAPPING)Marshal.PtrToStructure(singleBuffer, typeof(HBA_FCPTARGETMAPPING));
int numberOfEntries = int.Parse(singleFCPTargetMapping.NumberOfEntries.ToString());

//more memory required
if (singleResult == 7)
{

    //Now get the full FCPMapping
    int fullBufferSize = Marshal.SizeOf(typeof(HBA_FCPTARGETMAPPING)) + (Marshal.SizeOf(typeof(HBA_FCPSCSIENTRY)) * numberOfEntries);
    IntPtr fullBuffer = Marshal.AllocHGlobal(fullBufferSize);
    uint fullResult = HBA_GetFcpTargetMapping(hbaHandle, fullBuffer);
    if (fullResult == 0)
    {
        HBA_FCPTARGETMAPPING fullFCPTargetMapping = (HBA_FCPTARGETMAPPING)Marshal.PtrToStructure(fullBuffer, typeof(HBA_FCPTARGETMAPPING));
        //for (uint entryIndex = 0; entryIndex < numberOfEntries; entryIndex++)
        //{

         //}
    }
}

[StructLayout（LayoutKind.Sequential）]
公共结构HBA_FCPTARGETMAPPING
{
公共UInt32个条目；
public IntPtr SCSIEntry；/*包含映射的可变长度数组*/
}
//为1 FCPTargetMapping分配内存以获取条目数
int singleBufferSize=Marshal.SizeOf（typeof（HBA_FCPTARGETMAPPING））；
IntPtr singleBuffer=Marshal.AllocHGlobal（singleBufferSize）；
uint singleResult=HBA_GetFcpTargetMapping（hbaHandle，singleBuffer）；
HBA_FCPTARGETMAPPING singleFCPTargetMapping=（HBA_FCPTARGETMAPPING）Marshal.PtrToStructure（singleBuffer，typeof（HBA_FCPTARGETMAPPING））；
int numberOfEntries=int.Parse（singleFCPTargetMapping.numberOfEntries.ToString（））；
//需要更多内存
if（singleResult==7）
{
//现在获取完整的FCP映射
int fullBufferSize=Marshal.SizeOf（typeof（HBA_FCPTARGETMAPPING））+（Marshal.SizeOf（typeof（HBA_fcpscsicentry））*numberOfEntries）；
IntPtr fullBuffer=Marshal.AllocHGlobal（fullBufferSize）；
uint fullResult=HBA_GetFcpTargetMapping（hbaHandle，fullBuffer）；
if（fullResult==0）
{
HBA_FCPTARGETMAPPING fullFCPTargetMapping=（HBA_FCPTARGETMAPPING）Marshal.PtrToStructure（fullBuffer，typeof（HBA_FCPTARGETMAPPING））；
//对于（uint entryIndex=0；entryIndex

您无法让封送器封送可变长度结构。它根本无法做到这一点。这意味着您需要手动封送它

使用

AllocHGlobal

或

AllocTaskMem

分配结构

在计算结构的大小时，请确保考虑任何填充

使用

PtrToStructure

和

StructureToPtr

和指针算法手动封送数组

---

拥有一个带有单个数组元素的结构是非常值得的。正如你在问题代码中所说的那样。您可以使用它来封送结构的主要部分，并让封送器处理布局和填充。然后使用

OffsetOf

查找可变长度数组的偏移量，并逐个元素封送该元素

变更来源：分录[1]；收件人：条目[]；。您有一个指针数组，指针的数量由变量NumberOfEntries决定。分配的大小为sizeOf（Uint32）+sizeOf（NumberOfEntries*sizeOf（HBA_FCPSCSIENTRY）。第一个条目是指向数组的指针加上Uint32的偏移量。然后获取下一个条目add sizeOf HBA_FCPSCSIENTRY）。SCSIEntry成员应键入HBA_FCPSCSIENTRY。它不是指针。这是一个内联数组。

[StructLayout(LayoutKind.Sequential)]
public struct HBA_FCPTARGETMAPPING
{
    public UInt32 NumberOfEntries;
    public IntPtr SCSIEntry;    /* Variable length array containing mappings*/
}

//Alloc memory for 1 FCPTargetMapping to get the number of entries
int singleBufferSize = Marshal.SizeOf(typeof(HBA_FCPTARGETMAPPING));
IntPtr singleBuffer = Marshal.AllocHGlobal(singleBufferSize);
uint singleResult = HBA_GetFcpTargetMapping(hbaHandle, singleBuffer);
HBA_FCPTARGETMAPPING singleFCPTargetMapping = (HBA_FCPTARGETMAPPING)Marshal.PtrToStructure(singleBuffer, typeof(HBA_FCPTARGETMAPPING));
int numberOfEntries = int.Parse(singleFCPTargetMapping.NumberOfEntries.ToString());

//more memory required
if (singleResult == 7)
{

    //Now get the full FCPMapping
    int fullBufferSize = Marshal.SizeOf(typeof(HBA_FCPTARGETMAPPING)) + (Marshal.SizeOf(typeof(HBA_FCPSCSIENTRY)) * numberOfEntries);
    IntPtr fullBuffer = Marshal.AllocHGlobal(fullBufferSize);
    uint fullResult = HBA_GetFcpTargetMapping(hbaHandle, fullBuffer);
    if (fullResult == 0)
    {
        HBA_FCPTARGETMAPPING fullFCPTargetMapping = (HBA_FCPTARGETMAPPING)Marshal.PtrToStructure(fullBuffer, typeof(HBA_FCPTARGETMAPPING));
        //for (uint entryIndex = 0; entryIndex < numberOfEntries; entryIndex++)
        //{

         //}
    }
}